Method of making brake drums



Oct. 22, 1940.

D. J-. CAMPBELL ET AL 2,218,310

METHOD OF MAKING BRAKE DRUMS I Original Filed April 26, 1937 4 Sheets-Sheet 1 lnve \brs Ca phi.

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Afiome s gniMw ATQS 3 Oct. 22, 1940. 0.1.1. CAMPBELL ET AL v METHOD OF MAKING BRAKE DRUMS Original Filed April 26. 1957 4 Sheets-Sheet 2 Oct. 22, 1940. D. CAMP-BELL ET AL 2,218,810

METHOD OF MAKING BRAKE DRUMS Original Filed April 26, 1957 4 Sheets-Sheet 3 we on jIQonakl d. Campbe Qhar es .Dake Q.- M amSL ,M

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1940- D. J. CAMPBELL ET AL 2,213,810

METHOD OF MAKING BRAKE DRUMS Original Filed April 26, 1957 4 Sheets Sheet 4 Donald d. Qgmpjgil Charles W. Dake v w m Patented Oct. 22, 1940 UNITED STATES PATENT OFFICE- 2,218,810 METHOD or MAKING BRAKE DRUMS Mich., a corporation of Michigan Original application April 26, 1937, Serial No.

138,962. Divided and this application May 9,

1938, Serial'No."20G,756

' 2 Claims. (01...52-206) This invention relates to improvements in the method of brake drum manufacture, andparticularly to a molding thereof and for their'production, preferably of composite wrought steel and cast iron brake drums such as are used on motor vehicles.

' The'brake drum which is to he produced in-'- eludes a wrought metal brake drum shell or band which is lined with a lining of cast metal molecularly bonded therewith to provide in .effect an integral brake drum structure through which heat generated in the drum during the operation of the brake mechanism, when the braking shoes 7 frictionally engage thereagainst, passes uniformly 1;", through the drum where it is readily dissipated by the surrounding atmosphere. The brake drum when completed includes a supporting back or web also of wrought metal which may be either integral with the wrought metal shell described go or separately attached as by spot welding, riveting or other suitable connecting means.

' In our invention a novel mold and apparatus is provided for efiectively casting molten metal into engagement with the inner side of the wrought metal shell insuch' a manneras to secure an intermolecular joinder of the cast metal with the Wrought metal shell, thereby providing a lining of cast metal secured to the shell or band which serves as a support for the castmetal and gives resistance against breakage while the cast metal provides a superior braking surface. The invention includes many novel details of structure in the mold for practically and effectively attaining the intermolecular joinder of the cast metalwith the supporting shell or ring therefor and without chilling the molten metal or warping and distorting the shell. The temperature of the molten metal as poured into the'mold is very high and above the melting point of the supporting shell metal in order to attain the intermolecular joinder of thetwo. Incommercia1 practice the brake drum shell is of sheet steel and the cast metal is cast iron alloyed as may be desired.

An understanding of the improvements or invention for the attainment of the ends stated, as well as many others not specifically enumerated at this time, may be had from the following description, taken in connection with the accompanying drawings, in which:

Fig. l is a vertical section through a mold by means of which a plurality of cast metal linings of the composite brake drums may be simultaneously cast.

Fig. 2 is a plan view of, the mold, shown in Fig. 1. Figs. 3 and 4 are horizontal sections substantially on the planes of lines 3-3 and 4-'-4 of Fig. 1.

Fig. 5 is a vertical section, somewhat similar to that shown in Fig. 1, except the casting of the V liner to but one brake drum shell of a formed steel shell is secured; and shows the method as em:-

' ployed in producing one drum only.

Fig. 6 is an elevation and partial section of a completed drum shell or band.

Fig. 7 is a perspective view of one form of reinforcing ring which is located around the sheet metal shell for supporting the shell against enlargement, the inner side of which the molten lining a brake drum shell provided with annular ribs for providing better heat dissipation from the completed brake drum. 7

Like reference characters refer to likeparts in the different figures of the drawings.

Referring to Fig. 1, a'mold made of a plurality of superimposed sections or portions is provided. The lower mold section l is contained in a sur-' rounding flask 2 and rests upon a base3. A plurality of duplicate mold sections 4, as many as may be conveniently used, are placed in super: imposed relation, one over the other, above the lower moldsection I, said mold sections 4 being retained within flasks 5." Above the uppermost mold section 4 is a cope section 6 within flask "I; The adjacent upper and lower edge portions of the several flasks 2, 4 and 8 have outwardly extending flanges'over which, at proper spaced apart points, clampsB are located to hold the sections together;

Each of the mold sections 4 has a central cav ity, open at its under side, within which islocated the wrought metal brake drum'shell or band 9,

which is of substantially cylindrical form and at" its upper edges as located in the mold, has an inturned horizontal annular flange Ill. The lower edge portionof the-shell 9 is shaped preferably with an outwardly extending comparativelywide annular rib l l ,the lower edge of which terminates substantially flush with the lower side of the mold cavity 4. The mold sections 4, as well as 'the sections 1 and 6, are made from suitable moldingj sand deposited in the flasks in accordance with usual molding-practice arounda suitable pattern and I 5a which are now about to be described.

Around the brake drum ring 9 a cylindrical: channu'lar ringl2 of sheet "metal is locatedin .shell 9 and ring I2.

the upper and lower edges of the band portion when the channel is located in the space I4, bears against the outer side of the shell 9 above the pressed or rolled out rib I i The channel ring I5 is split at one side as shown in Fig. 7.

A core [6 is located within the recess of each mold section 4 which is surrounded by the brake drum shell 9, there being defined between its periphery and the inner side of the shell 9 a mold cavity IT. The cores [6 have alined vertical sprues [8, the upper ends of which join with the sprue openings l9 at the upper part of each of the mold sections 4, as shown. Associated with each mold section 4, are radial gates 20 extending outwardly, joining with the said sprue openings l9, and at their. outer ends connected to circular groove 2| from which a large number of spaced apart gates 22 extend outward and connect with the lower end of the mold cavity [1. The gates at 22 are spaced apart by interposed spacing projections 23, preferably from the mold section 4, and, as shown in Fig. 4, the gates at 22 widen laterally and decrease in vertical dimension from their inner ends outwardly. This provides for a substantially uniform rate of flow velocity from the gates into the mold cavity I1 and continuously around the lower end of the whole of cavity I! when the molten metal is poured into the mold. The upper pouring section fijwhich does not. have any mold cavity I1 to be filled with molten iron, is therefore shaped at its lower side to fill the radial gates 20 and groove 2| at the upper side of the next adjacent lower section 4.

At the upper side of each of the cores l6 are one or more recesses 24 (see Fig. 3) which provide overflow reservoirs for the surplus melted iron flowed through the mold cavity in contact with the inner periphery of the drum shell to heat the surface thereof to a temperature that will permit the cast metal lining to become molecularly joined with the drum shell and when it has reached the uppermost pointsin the cavity I'I. As shown, the upper or cope section 6 has a central pouring opening 25 at the lower part of which is a skim gate 26 resting upon the upper side of the next lowermost section 4. The metal, when poured in to the opening at'25, passes through the gate 26 and first fills the gates and the mold cavity connected therewith in the lowermost of the sections, thereby lining the shell 9 and its rib II with the cast metal. The gates are filled with metal 30 and the sprues with the metal at 29, while the overflow pockets at 24 are filled with the metal indicated at 28 in Fig. 1. The pouring of the molten metal is continued until it has reached above the skim gate 26.

With this construction of mold the sheet metal shells 9 are spaced from the sand of the mold sections 4 by the rings l2 and I5, thereby providing insulating air spaces l4 which prevents quick dissipation of heat and chilling of the molten metal when it impinges and engages the inner sides of the rings 9. The channel rings l5 in said annular air spaces hold the rings 9 against outward deformation which otherwise would occur on account of the softening and lessening of resistance of the rings 9 when the very high temperature molten metal comes thereagainst. When molten iron is used as the metal to be cast to make the lining l1 and comes against a steel brake drum shell 9 the temperature of the molten iron preferably will be considerably above that normally used in regular foundry practice. The temperature of molten iron as taken from cupolas in foundry practice is usually near 2500 F., but it may reach 2600 F. Therefore, heating such molten iron as it is taken from the foundry cupola in an electric or other furnace to raise the temperature for example to a higher temperature such as 2850 F. or at times to 3000 F. is desirable and ispreferred for the attainment of successful molecular fusion of the cast iron to the steel shell 9, which fusion must be such that there is'a complete intermolecular joinder of the cast iron and steel over their entire opposed areas where they come into contact engagement with each other. The annular rib H in the shell 9 is to provide an increased body of cast iron at the open side of the brake drum so as to resist rupture and withstand stresses which the brake drum has to withstand.

In Fig. 5 a steel brake drum shell is shown having the steel shell 9 and a continuous supporting web or back I00 which is merely a continuation of a flange I0 as shown in Fig. 1. When a shell 9 having an inturned flange I0 is lined with the cast metal at 21 so as to provide a composite steel and cast iron member, such as shown in Fig. 6, the drum is completed by permanently connecting a separate sheet metal supporting back to the flange at I0, usually by spot welding. In the mold shown in- Fig. 5 the supporting back is present in the sheet metal part of the drum by the continuation of the flange l0 into a back I00 as shown in Fig. 5.

In Fig. 8 the steel shell 9a, having the flange I0, is provided with outwardly extending heat dissipating corrugations 3| which are filled when the cast iron liner 21 is cast as molten metal thereagainst. In such case the strengthening and reinforcing ring l5a is split transversely and correspondingly corrugated, as at 32 in the band portion thereof to fit over the ribs 3|.

With this mold and with the method of casting described composite brake drums of steel and cast iron wherein the steel is used as an outer supporting shell for a cast iron braking band within and molecularly bonded to the steel shell is read ily produced in a practical manner.

The invention is defined in the appended claims and is to be considered comprehensive of all forms of structure coming within their scope.

This application is a division from our previously filed application filed April 26, 1937, Serial No. 138,962.

We claim:

1. The method of casting brake drums which consists in the steps of providing a mold having a core therein, placing a wrought sheet steel brake drum shell between said core and said mold, providing an annular air space around said shell for insulating purposes, reinforcing said shell at its outer side against deformation, and casting melted iron at a temperature above the melting point of the steel against the inner side of said shell so that the iron first contacts the lower portion of the shell and runs upwardly thereagainst.

2. The method of casting a brake drum which consists in the steps of providing a mold, placing a wrought steel shell within and around and spaced from a core in said mold, providing a drag for said mold below the same and saidcore with runners for the passage of molten iron to the bottom of the space between the core and shell, depositing molten iron in said runners and upwardly against said shell to fill the recess between the shell and the core, molecularly binding 7 said iron to said shell, placing an annular metallic band around said shell, providing an annular air space between said shell and mold for insulating purposes, and reinforcing said shell against out- I ward deformation. t

DONALD J. CAMPBELL. CHARLES W. DAKE.- 

